National Renewable Energy Laboratory (NREL) in November 2002 NREL/SR-510-33000 presented the concept of Bioethanol production plant and Combined Heat and Power (CHP) plant co-location, to utilize CHP heat and power in Biofuel production. The report presents an idea to use rest of the remaining biomass, referred as lignin, as part of the CHP fuel.
Christensen et al. defined a method and device for thermal hydralisation in patent US2010041119A Method and apparatus for conversion of cellulosic material to ethanol. The patent defines separation of lignin and co-firing it in a CHP device, which is connected to the power grid.
ST1/Ahokas et al. define a method and device for Bioethanol production in WO2009141495 (A1). The patent indicates dry matter to be used as biofuel to partly provide thermal energy to be used in hydrolyzing, fermentation, vaporization and dehydrating means.
Veolia water solutions & tech/Hoejsgaard define an apparatus for continuous hydrolysis in WO2013117686 (A1) using solid matter as fuel.
Water & Wastewater International magazine presented in the issue of Sep. 1, 2012 an example of thermal hydrolysis in actual waste water and sludge treatment. It concluded that best energy balance is reached when waste water sludge is treated with thermal hydrolysis but not dried. Dried sludge results better energy production, but requires more energy in drying process than is gained by burning less humid sludge.
VTT/Alakangas 2000 “Suomessa käytettävien polttoaineiden ominaisuuksia” (Characteristics of the fuels used in Finland) estimates the energy efficiency in bio based fuels as a function of dry mass content and effective caloric value.
Fossil fuels cause emissions that are harmful to the nature. Production of biofuels requires external energy. Production of the external energy for biofuel production decreases the efficiency of the biofuel production in terms of energy required to produce a unit of biofuel.